To date, there is little or no evidence of the ability to predict real- world benefit of hearing aids from electroacoustic data, which are performed in an anechoic environment as a measure of quality control among similar products. Clinicians, therefore, are faced with a clear understanding of how well a given listener will perform in everyday-listening situations. Directional microphone hearing aids (DMHAs) are known to improve speech intelligibility in adverse listening conditions. In this study, the directivity index (DI), an electroacoustic measure of microphone directionality, and speech-to-babble ratio (SBR) performance will be compared across an anechoic room (AR), an audiometric sound room (SR), a living room (LR), and a classroom (CR) for unaided (UA), omnidirectional microphone (OD), and diretional microphone (DM) listening conditions. The LR and CR will be included in the experiment to emulate common real-world environments that are moderately reverberant. The analysis will be aimed at determining the extent to which SBR performance in each of the listening environments is similar to , or different from, SBR performance in the other environments. Findings are expected to reveal the environment(s) for which the associated DI best predicts SBR performance in real-world listening situations, and the most realistic environment for measurements of DI.